1. Field of the Invention
The present invention relates to devices and methods for constructing tubular structural members. The tubular structural members can control the stiffness of various devices and structures. The present invention can be used with any type of sports equipment where the user will find it desirable to adjust or change the stiffness of the device, such as hockey sticks, lacrosse sticks, field hockey sticks, bats (for baseball, softball or cricket), golf clubs, fishing rods, skis, snowboards, pole vaulting poles, polo mallets, footwear, masts, scuba fins, bicycles, weightlifting devices, and oars. The invention also relates to methods of manufacturing these devices so that the desired stiffness may be set at the time of manufacture.
2. Description of Related Art
Adjustable sports equipment is known from U.S. Pat. No. 6,113,508 and U.S. Pat. No. 6,257,997 B1 that have a cavity in which a stiffening rod is inserted. The use of a stiffening rod, called a structural member, is taught into these references. The cross-section of the structural member can vary along its length with respect to its cross-sectional moment of inertia or plane of flexural resistance. Stiffness then becomes a function of the desired stiffness characteristic of the material or materials at that location and the arrangement of those materials. The present application incorporates disclosure of U.S. Pat. Nos. 6,113,508 and 6,257,997 B1, by reference.
In recent years, sports equipment manufacturers have increasingly turned to different kinds of materials to enhance their sporting equipment. In so doing, entire lines of sports equipment have been developed whose stiffness or flexibility characteristics are but a shade different from each other. Such a shade of difference, however, may be enough to give the individual equipment user an edge over the competition or enhance sports performance.
The user may choose a particular piece of sports equipment having a desired stiffness or flexibility characteristic and, during play, switch to a different piece of sports equipment that is slightly more flexible or stiffer to suit changing playing conditions or to help compensate for weariness or fatigue. Such switching, of course, is subject to availability of different pieces of sports equipment from which to choose.
That is, subtle changes in the stiffness or flexibility characteristics of sports equipment may not be available between different pieces of sports equipment, because the characteristics have been fixed by the manufacturer from the choice of materials, design, etc. Further, the user must have the different pieces of sports equipment nearby during play or they are essentially unavailable to the user.
Turning to various types of sports, it can be seen how the lack of adjustability in stiffness and flexibility may adversely affect optimum performance of the player.
Hockey
Hockey includes, but is not limited to, ice hockey, street hockey, roller hockey, field hockey and floor hockey.
Hockey players may require that the flexure of the hockey stick be changed to better assist in the wrist shot or slap shot needed at that particular junction of a game or which the player was better at making. Players may not usually leave the field to switch to a different piece of equipment during play.
Younger players may require more flex in the hockey stick due to lack of strength; such flex may mean the difference between the younger player being able to lift the puck or not when making a shot since a stiffer flex in the stick may not allow the player to achieve such lift.
In addition, as the younger players ages and increases in strength, the player may desire a stiffer hockey stick, which in accordance with convention means the hockey player would need to purchase additional hockey stick shafts with the desired stiffness and flexibility characteristics. Indeed, to cover a full range of nuances of differing stiffness and flexibility characteristics, hockey players would have available many different types of hockey sticks.
Even so, the hockey player may merely want to make a slight adjustment to the stiffness or flexibility of a given hockey stick to improve the nuances of the play. Such would not be possible unless the multitude of hockey sticks included those having all such slight variations in stiffness and flexibility needed to facility such nuances.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a shaft of a hockey stick to permit the user to adjust the stiffness of the hockey stick shaft. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a shaft of a hockey stick to permit the user to adjust the stiffness of the hockey stick shaft. U.S. Pat. No. 4,348,113 reveals insertion of juxtaposed mainstays into cavities of a shaft of a hockey stick to help make the stick withstand excessive damage resulting from wear caused by abrasion as the butt side of the hockey blade scrapes or hits the ice. U.S. Pat. No. 5,879,250 reveals insertion of a core into a shaft of a hockey stick to help the stick stronger and more durable to withstand high strains during the course of play. A series of grooves are formed in the core in an attempt to attain a desire center of equilibrium.
Tennis
Tennis players also may want some stiffness adjustability in their tennis rackets and to resist unwanted torsional effects caused by the ball striking the strings during play. The torsional effects may be more pronounced in the case where the ball strikes near the rim of the racket rather than the center of he strings. Thus, it would be desirable to lock in the stiffness characteristic close to the rim as opposed to just at the handle end.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a shaft of a tennis racquet to permit the user to adjust the stiffness of the tennis racquet. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a shaft of a tennis racquet to permit the user to adjust the stiffness of the tennis racquet.
U.S. Pat. No. 4,105,205 reveals one or more rotatable beams of rectangular cross section arranged within a cavity of the tennis racket for radically changing its stiffness. U.S. Pat. No. 5,409,216 reveals a shaft in the form of a double head ends for improving the grip on the handle, which may change the stiffness or flexibility of the racket due to a change in orientation of the double head ends relative to the racket head. U.S. Pat. No. 3,833,219 reveals spacer discs in a tennis racket, each disc having a width that exceeds its thickness. The spacer discs, if made of metal, may be made in varied weights and thickness to allow for adjusted handle weight as well as for adjusted grip sizes.
Lacrosse
Lacrosse players use their lacrosse sticks to scoop up a lacrosse ball and pass the ball to other players or toward goal. The stiffness or flexibility of the lacrosse stick may affect performance during the game. Players may tire so some adjustment to the flexibility of the stick may be desired to compensate. With conventional lacrosse sticks, such adjustment is not available.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a shaft of a lacrosse stick to permit the user to adjust the stiffness of the lacrosse stick. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a shaft of a lacrosse stick to permit the user to adjust the stiffness of the lacrosse stick.
Other Racket Sports
Other types of racket sports also suffer from the drawback of being unable to vary the stiffness and flexibility of the racket during the course of play to suit the needs of the player at that time, whether those needs arise from weariness, desired field positions, or training for improvement. Such racket sports include racquetball, paddleball, squash, badminton, and court tennis.
For conventional rackets, the stiffness and flexibility is set by the manufacturer and invariable. If the player tires of such characteristics being fixed or otherwise wants to vary the stiffness and flexibility, the only practical recourse is to switch to a different racket whose stiffness and flexibility characteristics better suit the needs of the player at that time.
Golf
Golf clubs may be formed of graphite, wood, titanium, glass fiber or various types of composites or metal alloys. Each varies to some degree with respect to stiffness and flexibility. However, golfers generally carry onto the golf course only a predetermined number of golf clubs. Varying the stiffness or flexibility of the golf club is not possible, unless the golfer brings another set of clubs of a different construction. Even in that case, however, the selection is still somewhat limited.
Nevertheless, it is impractical to carry a huge number of golf clubs onto the course, most rules limit the number of clubs that can be carried to 14. But, as each club has a slight nuance of difference in flexibility and stiffness than another., golf players prefer taking onto the course a set of clubs that are suited to the player's specific swing type, strength and ability.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a golf club shaft to permit the user to adjust the stiffness of the golf club shaft. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a golf club shaft to permit the user to adjust the stiffness of the golf club shaft.
Skiing, Snowboarding, Snow Skating, Skiboarding
Skis are made from a multitude of different types of materials and dimensions, the strength and flexibility of each type differing to a certain extent. Skis include those for downhill, ice skiing, cross-country skiing and water-skiing. Other types of snow sports devices include snowboards, snow skates and skiboards. Beginners generally require more flex and, as they progress in ability, much less.
Skiers generally do not carry with them a multitude of different types of skis for themselves use during the course of the day to suit changing skiing conditions or to compensate for their own weariness during the day. The same holds true for those who use snowboards, snow skates and skiboards.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a ski, snowboard or snowskate to permit the user to adjust the stiffness of the ski, snowboard or snowskate. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a ski, snowboard or snowskate to permit the user to adjust the stiffness of the ski, snowboard or snowskate.
U.S. Pat. No. 3,300,226 reveals elongated bars in skis. Each bar may be rotated to a desired orientation to vary the stiffness and flexibility of the skis. The bars have a width that exceeds their thickness. U.S. Pat. No. 4,221,400 reveals the use of prestressed curved rods, which are rotated to affect the amount of camber or predetermined curve in a ski. French Patent No. 1,526,418 reveals elongated rods in skis that may be rotated to a desired orientation to vary the stiffness and flexibility of the skis. The rods surround a stiffening bar having a width that exceeds their thickness. U.S. Pat. No. 4,592,567 reveals replaceable elongated flat bars attached to the top surface of a ski as a means to affect the flexure of a ski.
Ski Boots
Cross country and telemark skiing boots attach to the ski via a binding at the toe and have a free heel that allows the skier to stride on the snow in a motion similar to walking. The boots (or shoes) have flexible soles to allow a greater range of motion. Telemark bindings have a cable that runs around the heel of the boot to provide holding power, but also acts to exert pressure from the skier into the ski. Performance in cross country and telemark skiing can be greatly affected by the amount of pressure that is exerted by the skier through the boot/shoe into the ski. Different boots have different sole stiffness that skiers use to suit their particular style and needs.
Telemark skiers further change the amount of pressure that is transmitted into the ski by adjusting the tension on the cable. More tension will result in stiffening the sole of the boots and thus increase the pressure and control that the skier has over the ski. More sole stiffness provides more pressure which is needed for more control in steeper or icier conditions. Less stiffness reduces the pressure to allow for a smoother glide and more comfort in easier, flatter and softer snow conditions. It would be desirable to allow the skier to quickly and easily change the stiffness of the boot sole and thus change the amount of pressure that is to be transmitted into the ski, thereby altering the ski performance.
U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine into cavities of a boot to permit the user to adjust the stiffness of the boot.
Bicycle Shoes
Bicycle specific shoes are rigid and attach to bicycle pedals usually through a binding or clip mechanism that prohibits the shoe from slipping off the pedal. The shoe is positioned on the pedal so the ball of the foot is directly over the pedal. The rider's foot flexes as the pedal moves through its range of motion and the rider depends on his/her foot and ankle strength to effect additional pressure onto the pedal and thus increase the speed or power delivery.
It would be desirable to supplement the rider's own ankle and foot strength by making the sole of the shoe stiffer and increasing the leverage the rider has on the pedal. Preferably, riders will be able to adjust the stiffness of the shoe sole according to their strength, road/course conditions.
U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine into cavities of a shoe to permit the user to adjust the stiffness of the shoe.
Running Shoes, Training Shoes, Basketball Shoes
The transmission of the shoe wearer's strength (power) from their legs into the ground is directly affected by the sole stiffness of the shoe. Runners may gain more leverage and thus more speed by using a stiffer sole. Basketball players may also affect the height of their jumps through the leverage transmitted by the sole of their shoes. If the sole is too stiff, however, the toe-heel flex of the foot is hindered.
It would be desirable that the shoe wearer have the ability to tailor the sole stiffness to his/her individual weight, strength, height, running style, and ground conditions. Preferably, the shoe wearer may tailor the stiffness of the shoe sole to affect the degree of power and leverage that is to be transmitted from the wearer into the ground.
U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine into cavities of a shoe to permit the user to adjust the stiffness of the shoe.
Batting
Sports such as baseball, softball, and cricket use bats to strike a ball. The batter may want to select a bat that is more stiff or flexible, depending upon the circumstances of play. Conventional bats only permit the batter to choose from among a variety of bats of different weights and materials to obtain the desired stiffness or flexibility. However, adjusting the stiffness or flexibility characteristics for a given bat is not feasible conventionally. Further, there is no practical way conventionally to determine which batting flexure and stiffness is optimal for batters with a single batting device.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a bat to permit the user to adjust the stiffness of the bat. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a bat to permit the user to adjust the stiffness of the bat.
Polo
Polo players use mallets during the course of the polo match. Changing the stiffness or flexibility characteristics is only available by exchanging for a different mallet with the desired characteristics.
U.S. Pat. No. 6,113,508 and U.S. Pat. No. 6,257,997 reveal the use of a rotatable flexure resistance spine into cavities of a polo mallet to permit the user to adjust the stiffness of the polo mallet.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a polo mallet to permit the user to adjust the stiffness of the polo mallet. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a polo mallet to permit the user to adjust the stiffness of the polo mallet.
Sailboating and Sailboarding
Masts of sailboats and sailboards support sails, which are subjected to wind forces. These wind forces, therefore, act through the sails on the mast. The mast may be either a rigid or flexible structure, which may be more desirable under certain sailing conditions. If the mast is flexible, tension wires may be used to vary the tension of the mast. Otherwise, the flexibility and stiffness characteristics of mast are generally fixed by the manufacturer, making it impractical to alter the mast flexibility or stiffness in different directions to suit changes in wind direction or the needs of the sailor.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a mast to permit the user to adjust the stiffness of the mast. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a polo mast to permit the user to adjust the stiffness of the mast.
Canoeing, Rowboating and Kayaking
Paddles for canoes, row boats, and kayaks are subjected to forces as they are stroked through water. The flexibility or stiffness of the paddles, while different depending upon its design and materials, is fixed by the manufacturer. Thus, a rower who desired to change such characteristics would need to switch to a different type of paddle. Carrying a multitude of different types of paddles for use with a canoe, row boat or kayak, however, is generally impractical for the typical rower from the standpoint of cost, bulk and storage.
U.S. Pat. No. 6,113,508 reveals the use of a stiffening rod in cavities of a paddle to permit the user to adjust the stiffness of the paddle. U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine in cavities of a paddle to permit the user to adjust the stiffness of the paddle.
Pole Vaulting
Pole vaulters use a pole to lift themselves to desired heights. The pole has flexibility and stiffness characteristics fixed by the manufacturer. The pole vaulter must switch to a different pole if the characteristics of a particular pole are unsatisfactory.
Fishing Rods
Fishing rods are flexed for casting out a line. The whip effect from the casting is affected by the stiffness or flexibility of the rod. Depending upon the fishing conditions and the individual tastes of the user, the user may prefer the rod to be either more flexible or more stiffer to optimize the whip effect of the cast.
U.S. Pat. No. 6,257,997 reveals the use of a rotatable flexure resistance spine into cavities of a fishing rod to permit the user to adjust the stiffness of the fishing rod.
U.S. Pat. No. 3,461,593 reveals elongated inserts in a fishing rod that may be rotated or twisted to a desired orientation to vary the stiffness and flexibility of the rod. The inserts have a width that exceeds their thickness and may be configured into any of a variety of different geometric shapes.
Exercise Equipment
Users of weight resistance equipment require different levels of resistance according to the particular exercise and their level of fitness. Ease of adjusting this resistance is desirable to maximize time spent in the exercise and minimize the time spent in setting up the equipment.
U.S. Pat. No. 6,257,997 reveal the use of a rotatable flexure resistance spine in a weight resistance unit to permit the user to adjust the level of resistance.
As defined in this application, sports equipment covers any type of rod, stick, bat, racket, club, ski, board, mast, pole, skate, paddle, mallet, scuba fin, footwear, exercise machine or weight bench that is used in sports. The sports equipment flex either (1) to strike or pick up and carry an object such as a ball or puck (hockey, lacrosse, batting, golf, tennis, etc.), (2) to carry a person (pole vaulting), (3) to cast out a line (fishing rod), (4) to engage a frictional surface (such as skis or footwear against the ground, snow or water or scuba fins against the water), or (5) to respond to forces (such as the wind forces against a sail or muscular forces exerted when using an exercise machine or weight bench).